Holley Carburetor Dates - How to Decode

[JWH]

This is an explanation of the date codes stamped into Holley carburetors that was posted by Dan Case on the SAAC website back in 2018. I am re-posting as a stand-alone post and new subject line that will hopefully help with future searches. Thank you Dan for the excellent explanation of Holley date codes.
Jeff


Holley® Carburetor Date Codes


Part I  O.E.M. Carburetor Date Codes

O.E.M. models, O.E.M. assembly line models, utilize a three digit date code; numbers or numbers and letters are stamped just below the Holley "List" number on the front face of the choke housing air horn. (Service assemblies set aside during production for making cars will have dates in the production time frame.)

Example:      List - 3259
                    4 B 5

The first digit signifies the year the carburetor was manufactured, 1964 in this example.

The second digit represents the calendar month of production, in our example December. The table below details the complete set of twelve month codes.


   Month Codes (Center Digit Of Date Code) for O.E.M. Carburetors

                           Month            Code

                           Jan. ------------- 1   
                           Feb. ------------- 2
                           Mar. ------------- 3
                           Apr. -------------  4
                           May  ------------- 5
                           Jun  -------------  6
                           Jul  -------------   7
                           Aug  ------------- 8
                           Sep  ------------- 9
                           Oct  -------------  0
                           Nov  ------------- A
                           Dec  ------------- B


The third digit designates the week of the month produced, the example above was made during week five.

Therefore the List - 3259 above, for a 1965 MUSTANG GT350 289 c.i.d. engines, was manufactured during the fifth week of December 1964.





   II Service Replacement Carburetor Date Codes

Service replacement carburetors, those available over the counter years later at O.E.M. dealers, speed shops, auto parts stores, etc, utilize a four digit date code; numbers only appear in this case, stamped in the same location as before under the "List" number. The service unit codes are expresses as "Julian" dates with the model year of manufacture indicated by the additional and last of the string fourth digit. The Julian date codes table for service models is given below.         

   Month Codes (First Three Digits) for Service Replacement
   Carburetors

             Month          Julian Date          Leap Years *

              Jan. ---------- 001 - 031 ---------- 001 - 031
               Feb. ---------- 032 - 059 ---------- 032 - 060
              Mar. ---------- 060 - 090 ---------- 061 - 091
              Apr. ---------- 091 - 120 ---------- 092 - 121
              May  ---------- 121 - 151 ---------- 122 - 152
              June ---------- 152 - 181 ---------- 153 - 182
              July ---------- 182 - 212 ---------- 183 - 213
              Aug. ---------- 213 - 243 ---------- 214 - 244
              Sept.---------- 244 - 273 ---------- 245 - 274
              Oct. ---------- 274 - 304 ---------- 275 - 305
              Nov. ---------- 305 - 334 ---------- 306 - 335
              Dec. ---------- 335 - 365 ---------- 336 - 366

         * Leap Years: 1964, 1968, 1972, 1976, 1980, etc.

As an example of a service replacement carburetor lets examine a current Ford Motorsports Boss 429 replacement unit.

   List - 4647
             2916   

This carburetor is definitely a service model since it has a four digit date code. The fourth digit signifies 1986 (It was purchased from Ford in early 1988.). The Julian date indicates that it was manufactured during October. Even though this carb "looks" original on the BOSS 429 engine it occupies, it can not be "original" for a 1969 model car when it was not manufactured until October 1986.


The List-2804 and List-2805 assemblies have wide possibilities for dates as they were a) used on several types of new cars, b) used for more than one model year, and c) used in racing also.

These two models were introduced as a running change during the 1963 model year run of 427 Galaxie 8V engines and were used through the 1967 model year. They were standard equipment on:
- part of the 1963 model year for Ford Galaxies with  427 8V engines
- 1964 model year Galaxie 427 8V engines
- 1965 model year Galaxie 427 8V engines
- 1966 model year CSX31xx 427 Cobras with 8V engines
- 1967 race season Group II 289 race engines in Shelby American Group II Mustang racers
- 1967 model year GT500s with 428 8V engines

There were lots of them installed on new engines over several years. They also seemed to be a popular over the counter offering at least through 1970. The only trick seems to be finding great cores of a particular date time frame with their original dated assembly tags intact.


« Last Edit: November 14, 2018, 06:17:53 PM by Dan Case »
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Dan Case
1964 Cobra owner since 1983, Cobra crazy since I saw my first one in the mid 1960s in Huntsville, AL.

[Chris Thauberger]

Way to go Jeff. Great information. Thanks for reposting.

Thanks to Dan Case for the original post/info. 

Chris

[Side-Oilers]

Thanks for all the research, and for sharing it.

[JWH]

Again, all of the information on the date codes was put together by Dan Case. So all credit to Dan. I simply copied and posted Dan's information again with a new subject line to make it easier to find in future searches. Thank you Dan!

[Dan Case]

Again, all of the information on the date codes was put together by Dan Case. So all credit to Dan. I simply copied and posted Dan's information again with a new subject line to make it easier to find in future searches. Thank you Dan!

You are welcome.